The resources are generic and don’t respond to the specific issue I have here

The resources are specific to creating stable numbering. They are only generic in the sense that numbering schemes vary.

If you keep repeating the same mistake you cannot expect a different outcome.

They are the only known way to fix, long term, the problem you have. They are the only known way to get stable multilevel list numbering in Word. They are generic in that they apply to every version of Word since Word 97 (although there is a separate page for menu versions).

What you have done may work for you. I cannot tell from screenshots what is happening in the document structure.

One thing that can happen rather easily when using the buttons on the home tab for numbering is creating and having multiple lists in a document and having them interfere with one another or confuse one another.

That is what is going on in the document. If only people would follow the advice they're given...